Process for recovery of metals from scrap and metallurgical residues



Aug. 30, 19.38. v c. 8. WHITE 2,128,548

PROCESS FOR RECCVERY OF METALS FROM SCRAP AND METALLURGICAL RESIDUES Filed July 25. 1937 H1)" or Q v z gen NITRIC ACID SUPPLY TANK Waltz uh ,dcicz Old 262' .z'zzzaazanm'wicd 9 Patented Aug-30,1938 I 2,128,548

UNITED STATES PATENT OFFICE PROCESS FOR RECOVERY OF MET ALS SCRAP AND METALLURGICAL RESIDUES Clarence B. White, Philadelphia, Pa. Application July 23,1937, Serial No. 155,323

7 ".1 Claim. (Cl. 204-45) This invention relates to an economical method may be used in succession. The tin is recovered of recovering metals such as copper, tin, lead and as a precipitate of metastannic acid while the zinc from scrap material, metallurgical 'by-prodsolution is drawn off and electroiyzed by a low nets and residues containing metals in the form voltage current in the electrolytic depositing of alloys. tank 8. 5

The primary object of the present invention is The electrodes 9 are preferably of insoluble or to eliminate the partial furnace refining which is substantially insoluble material. The copper is usually employed at the present time in metal deposited on the cathodes as pure electrolytic recovery and to greatly reduce the expense of copper, the lead being deposited on the other 10 recovery. electrodes in the form of black oxide of lead. 10

The scrap materials and commercial residues After the removal of the copper and lead, the ordinarily contain copper, tin, lead and zinc tospent acid from the electrolytic tank is conveyed gether with impurities such as nickel, antimony, to the spray head iii of the uppermost condenser iron etc. -My,invention is more speciflcallydisection c.

,rected to the recovery of the metals by leaching The nitric oxide gas from the leaching tower 15 and electrolysis. Heretofore the use of nitric 3, together with the oxygen from the air or OXY? acid as the leaching agent or solvent by which gen supply, pass into the lower part of the lowest to obtain a solution of all of the metals, has not scrubbing section M of the condenser and perbeen commercially feasible on account of the colate upwardly through the mass of broken great expense of the acid employed. I have destone I5 or other suitable rubble, to thereby comvised a process in which the nitric oxide resultblue with the spent acid entering through the ing from the reactiondf the acid and the metals spray heads l6 and thus replenish the supply of of the scrap material is recovered to repeatedly nitric acid. replenish the leaching agent in a continuous The recycling of the spent acid in countercycle. current'relationship to the flow of nitric oxide gas 25 The accompanying drawing is a schematic ilconstitutes a continuous cyclic renewal of the lustration of apparatus for practicing my process nitric acid solvent. This is of very great imporof recovering metals from scrap or metallurgical tance and .is in fact, a-vitail controlling factor by-products. in the' practical recovery of metals from metal- In carrying out my process the granulated ma-. lurgical by-products by acid solvents on a com- 30 terial is placed in a leaching tower 3 where it is mercial scale.

subjected toa continuous shower or spray 4 of I claim:-

nitric acid from a suitable supply tank 5, 150- A continuous cyclic process for treating scrap gether with a suitable supply of oxygen or air. metal and metallurglca by-p oduct materals con- The reactions which take place are as follows:-- tainlng tin, copper and lead to recover said metals, 35

which comprisesthe cyclic use of nitric acid as a solvent, leaching said materials with-said solvent with the evolution of nitrous oxide, passing the nitrous gases to an absorbing tower, continuously'passing the solution from the leaching 40 In each case, it will be observed, nitric oxide tank to an electrolyzing tank, with the provision (NO) is evolved. In order to convert this into of a filtering tank between the leaching and elecnitric acid, the addition of oxygen is' necessary. trolyzing tanks to precipitate the tin as metas- The reaction in oxidizing nitric oxide to form tannic acid, electrolyzing the copper and lead nitric acid is substantially as follows: from the solution and continuously passing the 45' I spent acid from the electrolyzing tank to the g 26 fg m0 absorbing tower in counter-current relationship f g 2 6 H tothe nitric oxide resulting from the leaching 3+ 2 operation to regenerate the nitric acid for use in The solution drawn from the bottom of the the leaching operation. 50

tower is decanted in the filtering tanks 1, which CLARENCE B. WHITE. 

